Show Menu

Alvl P1: Particles (ch1/2) Cheat Sheet by

aqqa A-level physics year 1 (yr12) particles and nuclides/fundamental particles : chapter 1/2

Particle Forces

exchange particles
strong nuclear
none- >4fm, attrac 0.5<x<4fm, repul <0.5fm
charged particles
weak nuclear
the strong nuclear force holds nucleons together in a nucleus. the repulsion at <0.5fm stops the nucleus imploding.

specific charge

specific charge:
charge to mass ratio

for an atom, is the charge (typically proton number unless an ion then the charge eg 2+ only) over the overall mass (proton and neutron number)

nuclear decay equations

unstable nuclei decay to become more stable emitting radiation.

these can ionise other atoms/­mol­ecules which can be dangerous

Alpha decay (larger nuclei):
4 on the top, 2 on the bottom

Beta decay (smaller nuclei):
+ - p>n
- - n>p

**make sure lepton numbers are balenced
eg. beta- decay has anti electron neutrino

gamma radiation:
is a high energy EM wave that can be emitted but this isnt due to decay but due to nucleus being in an metastable state (excess energy)

in a decay equation you would write the product number at the top with a small m
in a separate equation you take the element with the m and write it out with the product being without the m and the gamma ray


charge, energy and momentum, baryon­/lepton number must all be conserved in any intera­ction.
strang­eness doesnt need to be conserved, only in strong intera­ction

- particle decay > strang­eness is not always conserved
- pair production > strang­eness is always conserved

- strange particles are produced by strong intera­ction
- to conserve strang­eness they are always created in pairs
eg. p + p = us-s
- they decay via weak intera­ction but don't need to be created in pairs (don't have to be conserved)

proving conser­vation: (Relating to particle intera­ctions)

B+/- --> occurs in a neutron (decay) - B+ = p>n
electron scatter --> come close and repel due to charge
P-N bond --> occurs in nuecleus due to strong force (also em however em is weaker than strong)
electron capture --> electron captured by a proton, therefore exchange particle is always from the proton (W+)
E-P collision --> electron collides with proton so exchange particle comes from the electron (w-)

Annihi­lation and pair production

these are possible due to the fact that mass can be converted ubti energy and vice versa

particle and antipa­rticle collide- mass is converted to two photons

minimum energy­/fr­equ­ency:
2mc2 = 2hf

if the particles have kinetic energy this is added to the photons energy

Pair produc­tion:
a photon of sufficient energy is converted into a particle and its antipa­rticle

minimum freq photon for this:
hf = 2mc2

if photon has more than minimum needed, it is converted into Ek


No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          A-Level Physics Key Terms Cheat Sheet
          Alvl P1: energy levels and particles of light(ch3) Cheat Sheet
          Alvl P2: Magnetic Fields (ch16) Cheat Sheet

          More Cheat Sheets by MostAncientDream

          Alvl P2: radioactive decay (ch11) Cheat Sheet
          Alvl P1: work, energy and power (ch6) Cheat Sheet
          Alvl P2: capacitance (ch6) Cheat Sheet